The source that matters ($) for that information is the ISP. The ISP's access to that information can be extremely cumbersome.

In any case, the particulars depend on that ISP.

(The problem of trying to limit data volume ("usage") by limiting bandwidth is that the typical monthly usage allowance is a tiny fraction of the total channel capacity in a month. A 25/10 Mb/s DSL line can move 300 GB in 20 hours. Thus, to limit monthly usage to 300 GB, the total data rate must be reduced to 3%, or something like 1 Mb/s down and 64 kb/s up.

This is similar to Zip-car rental, where you might have a daily allowance of 200 km. To ensure the distance limit by limiting the speed, the speed would have to be limited to 8 km/h. Obviously this is not a sensible "solution".)